tree d931df27d5dbb470dadcef4e9817ff70606aa58d
parent f3de395812542eb9abb8c4ea7f8181140ed2f0b0
author Emmanuele Bassi <ebassi@gnome.org> 1576254895 +0000
committer Emmanuele Bassi <ebassi@gnome.org> 1576254895 +0000

Add a G_DECLARE macro for "protected" types

Certain libraries want to provide types that are derivable for internal
users, but final for any external consumer of the API. Other languages
use the term "protected" to refer to this kind of type visibility
attribute.

Since we're providing macros to declare derivable and final types, we
should also provide a macro for declaring protected types.

The mechanism is the same as the other G_DECLARE macros; protected
types:

 - define an opaque type for the instance, like G_DEFINE_FINAL_TYPE
 - define an opaque type for the class
 - define cast and type check functions for instance pointers, for
 public consumers, and cast and type check functions for class pointers,
 for internal consumers
 - omit an accessor for retrieving the class structure from the instance
 structure, as it would be pointless to do so